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sticky Astrophotography Done with the iEXOS-100, EXOS 2, and G11 Post your Pictures and Details! Lets Show What These Mounts Can Do. #iEXOS-100 #G11 #EXOS2 #astrophotography


myron_wasiuta
 

Gorgeous images Jim!
Myron


On Sep 26, 2019, at 10:18 PM, Jim McKee <mckeejh@...> wrote:

[Edited Message Follows]

It was suggested that the EXOS-2 owners also post successful photos in a single thread.  AP on the EXOS-2 is a path that takes many months to get all the pieces to work together, especially for us beginners, but on a clear night, the EXOS-2  is a very capable mount.   So here is my post from last night on the Eastern Shore of Maryland.  It was very clear with a much reduced amount of haze/city lights.

The below are the result of 15 subs each w/ Darks at 640 ISO and 8 minute exposure times. PHD2 tracked well at RA of 1.1" and DEC of .65".  RA and DEC all had periodic excursions of as much as 2-3 arc-sec, but they all seemed to settle out and tracking was consistant for about 4 hours.  While they all looked like saw-teeth patterns, RMS was satisfactory.
M31, M33, M45

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--
Scope:        Orion EON 115mm APO
Mounts
:      ES EXOS2-GT w/ PMC-8
Cameras:   Canon 6D Astro Mod, Canon 7D2, 1D Mk 2, EOS 60D Asto Modified
Lens:
          Canon EF 100-400mm f/4.5-5.6L IS II
Misc:          TELRAD, ZWO ASI120MM Guide Camera, Astromania 60mm Guidescope, Senso Sesto Focus Motor
Software:   EXPLORESTARS IOS & WIN, Stellarium. Backyard EOS, StarTools, APT, DSS
Computer:  Dell Latitude E5450, Windows 10


asanmax@...
 

Crescent Nebula
Scope: Celestron C5, FL=1300mm
Camera: Canon T3i modified
Guider: 37mm/130mm with AR0130 sensor
54x90sec exposures at ISO 3200
Stacking in DSS, processing in PhotoShop, 60% crop.

Bortle 8 city sky


asanmax@...
 

Triangulum galaxy
Scope: Celestron C5, FL=1300mm
Camera: Canon T3i modified
Guider: 37mm/130mm with AR0130 sensor
36x90sec exposures at ISO 3200
Stacking in DSS, processing in PhotoShop, 70% crop.
Bortle 8 city sky


asanmax@...
 

The Great Pegasus Cluster
Scope: Celestron C5, FL=1300mm
Camera: Canon T3i modified
Guider: 37mm/130mm with AR0130 sensor
20x90sec exposures at ISO 800
Stacking in DSS, processing in PhotoShop, 50% crop.
Bortle 8 city sky


Jim McKee
 

I am still in research mode regarding guiding.  I don't know if seeing was part of the problem.
Tough night.  DEC was all over the place so I turned off DEC guiding.  DEC guiding would be nice for a about 2 minutes, then shoot north 3 arcsec, then stabilized, guided well for 2-3 minutes then shoot south to 3 arcsec.  This just repeated from 9:30pm to 12:30am.  I finally turned off DEC guiding and DEC stayed steady for next 2.5 hours at RMS of no more than 1 arc sec.   Shot 22x4 min of M81/M82.   Photo might be better focused if guiding was lower, but I am happy with the results after trying unsuccessfully to adjust DEC guiding.
 
Here is a processed image on Astrobin. I am still working out how to make the arms of the galaxy more prominent.
--
Scope:        Orion EON 115mm APO
Mounts
:      ES EXOS2-GT w/ PMC-8
Cameras:   EOS 60D Asto Modified
Misc:          TELRAD, ZWO ASI120MM Guide Camera, Astromania 60mm Guidescope, Senso Sesto Focus Motor
Software:   EXPLORESTARS IOS & WIN, Stellarium. NINA,  APT, DSS, PixInsight, Photoshop CC
Computer:  Dell Latitude E5450, Windows 10


Mark Christensen
 

Very respectable shot.

Your DEC puzzle is probably caused by backlash and the fact that you were very precisely aligned on the pole. Maybe too precisely.

Sounds counter-intuitive but having very precise polar alignment means there is virtually no (and it is also a function of the part of the sky you are looking in relative to the error that is there) DEC drift. Drift is usually systematic - it is constant during the exposure (but can change with orientation over time - see Mike Covington's books).

Having a small amount of systematic DEC drift means guiding corrections will always be in one direction and if the scope is slightly miss-balanced (similar to the "heavy east rule" for RA) then the DEC gear is always in contact at the same side of the worm wheel and hence never reverses so backlash never appears once it is worked out during the initial (a few minutes) time in which the guiding stabilizes. I see this all the time with my mounts (G11 and EXOS-2GT).

If there is no systematic DEC drift then you're at the mercy of the atmosphere, which can cause the DEC error to go in either direction and then backlash will be a problem. So that is probably why it worked better with DEC guiding disabled.

Trying to remove backlash by tightening up the gears is usually overdone, which then produces binding. With mounts of this class better to figure out how to avoid it in the first place, either by turning off DEC guiding (if your polar alignment is very good) or by only allowing DEC guiding (an option in PhD and PhD2) in only one direction (North or South). I usually have to do the latter since I rarely can see the pole in my backyard.

Mark Christensen


Jim McKee
 

Thanks Mark,

 

Sharpcap has given me great PA’s within 20 arcsec.    I am going to put a checklist together and see if I can isolate the issues to include the idea of imprecise PA.

 

I got out tonight at 7:30 and made the following adjustments to my configuration of PHD2 before doing some test guiding and shooting:

 

1)   Turned off Dither in the shooting sequence of NINA.

2)  Reset guiding parameters to default values.

3) Set DEC compensation to “on” (Check box checked) based on PHD2 user guide (quoted below)


 "Use Declination Compensation' - if PHD2 can get pointing information from the mount via an ASCOM connection ('Mount' or 'Aux'), it will automatically adjust the RA guide rate based on the current declination.  This box should normally be left checked except in unusual cases.  For example, SiTech mount controllers may apply a compensation automatically, in which case the box should be left un-checked.  Don't confuse this option with 'Declination backlash compensation', which is an entirely different feature.

 

4) Set Dither to Spiral Mode  based on PHD2 user guide (quoted below)

 

'Spiral mode' - tells PHD2 to dither with fixed-size amounts in a clockwise spiral pattern.  This can be a good choice when the imaging camera has significant fixed-pattern noise or the mount has a troublesome amount of Dec backlash.”

 

----------------------------

 

Again, I had great PA before I started (I hadn't seen your note yet)

I then shot M33  (3 lights of 480sec) with no dither.  Guiding was near perfect.   RA varied between 1.2 and .8 Arcsec.  DEC varied between .8 and .6 arcsec.  There were no excursions in DEC for the entire 18 minutes.

 

I turned off DEC Compensation and started guiding again and didn’t have any problems for 10 minutes,  So that doesn’t seem to be the issue.

 

 Even as clouds started to close in, guiding stayed nicely on track until the star SNR dropped below 12db and the star then disappeared.

 

I am disappointed I got clouded in at9pm, but i will walk through the following items and see if I can establish cause/effect next time out.

 

Using tonight’s settings as a starting point:

1)   Turn on dither

2)    Set Polar Alignment “off perfect” by 2 arcsec ]

3)   Set a back-heavy DEC balance

4)    Set DEC guiding to reverse on meridian flip (Jerry’s recommendation ) and guide on each side of meridian

 

 


--
Scope:        Orion EON 115mm APO
Mounts
:      ES EXOS2-GT w/ PMC-8
Cameras:   Canon 6D Astro Mod, Canon 7D2, 1D Mk 2, EOS 60D Asto Modified
Lens:
          Canon EF 100-400mm f/4.5-5.6L IS II
Misc:          TELRAD, ZWO ASI120MM Guide Camera, Astromania 60mm Guidescope, Senso Sesto Focus Motor
Software:   EXPLORESTARS IOS & WIN, Stellarium. NINA,  APT, DSS, PixInsight, Photoshop CC
Computer:  Dell Latitude E5450, Windows 10


kmagin72186@...
 
Edited

Witches broom taken with an unmodified sony A7rIV
Bortle 5 skies
Almost full moon

42x3min with broadband filter
17x3 min with Thousand Oaks LP-2 Narrowband
ISO 800

Batched and edited with Pixinsight
HaRGB merged in Pixinsight
Final adjustments in Photoshop

William Optics 103

Payload total with weights was 22.1 lbs

I would like to get some more Ha lights, but clouds rolled in and I am only 2 weeks into this new hobby so I have time.





asanmax@...
 

Holy smokes! That's a lot of weight, I'm far behind with my 14 lb total weight.
Great image! May I know what skies you were imaging under?


kmagin72186@...
 

I am under bortle 5 skies.  I wanted to push the mount to the limit and see what it could do while I waited for my heavy duty tripod and azimuth adjuster to come in.  It seemed to handle it fine with the legs in.  Raised up was a little wobbly.  Now with the heavy duty tripod I can also mount another dslr for some wide shots.


Vince White
 

We had some clear skies recently here in Houston and I thought I would share an experiment I did shooting in my backyard with awful Bortle 9 skies.  I was honestly surprised this much detail can be resolved in basically white skies.  This did take a long time to process all ~1000 photos and fiddling in PixInsight.

M31, 800x13sec lights, 30x darks, 30x flats, 100x bias @ ISO 800, no UHC filter


PS, my guiding setup should be complete this weekend, so I should hopefully have some further experiences to share soon.
--
Mounts: ES PMC-8 EXOS2-GT
Scopes: BRESSER 208mm f/3.9 Newt + ES HR Coma Corrector, Celestron C90 Mak
Cameras:  Canon 5DmkII, Canon EOSm
Misc: 2" Optolong UHC filter, Raspberry PI 4
Software: INDI + Kstars + EKOS, DeepSkyStacker, GIMP, Lightroom


Wes Mcdonald
 

So nice.  Amazing performance from the iexos.  
Wes.


--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Wes Mcdonald
 

13 sec exposures...wow.  Got some dust lanes.  Nice.  Wait till you guide and go deeper.
Wes.


--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


kmagin72186@...
 

triangulum galaxy

53x3min with light pollution filter. Same setup as the prior post


 

Beautiful work!

And... The Little Engine That Could!  Pretty amazing :-)

--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


asanmax@...
 

Great pics, I personally like to image at higher focal lengths on this mount.


kmagin72186@...
 
Edited

My issue with the higher focal length was not fitting in larger nebulas.  With the 61mp the a7riv offers I can shoot APS-C /super 35mm and still get 26.2 mp offering plenty of resolution for smaller targets.  

Like with the veil nebula, it was taken full frame because I wanted some of the surrounding nebula, but I could just get the witches broom in aps-c.  It gives me some more versatility 


asanmax@...
 

That's one of the positive sides of having a hi-res sensor. By the way, I was planning on imaging the North America nebula at 200mm tonight, but you reminded me that I have never shot the Western Veil nebula using this mount.
Currently imaging with my C5 scope at 1300mm and I should say I've never seen such great tracking with the total RMS sitting below 1 arcsec all the time between dithering actions.


Wes Mcdonald
 

The thing about long focal length is the pixel scale of the imaging array can easily get far smaller than the seeing.  The pixel scale is computed by 

P*206.3/f.

P = pixel size in micrometers
f = focal length in mm

As can be seen, the longer the focal length the smaller the pixel scale.  

The array essentially samples the image.  If the image resolution is limited by seeing to 2 arc seconds there is really no reason to sample more than 1 arc second (2x, although others argue even less oversampling).  Thus an image for which the pixel scale is more than 2x can be binned without fear of loss of detail and such binning will likely improve the appearance of stars.

A side note related to this is the guiding performance.  In principle if the guiding is better than the imaging pixel scale it is good enough.  That guiding performance shown is outstanding, likely for just about any imaging we could do with an iexos.

Wes





--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


kmagin72186@...
 

My tracking was a little worse than yours, but given there was 22lbs on it and that my location is a second story deck with kids and dogs running around causing some shake I cant be upset.  I only had to ditch 2 subs.

With the new HD tripod and additional weights the tracking was rock solid, under 1 to the point PHD actually gave me a warning that the calibration was significantly different.

Advice on the veil is take longer and more lights than you think you will need and under bottle 8 a narrowband filter will do wonder in bringing out the detail.  It's a hard target and I probably should have chosen a different target as my second ever target.  It was high in the sky so I figured I was in it to win it.